Step #4
New Project (did both, ‘Auto’ settings for an UHD and a fullHD one), add clips, hit Play … okayyyyyyy Playhead jumps every ~10 frames , due to ‘stillness’ of clips hard to judge, wether this is a GUI problem, or if poor MacMini offers me 0.2fps here. And lots of Activity :

Step #5
Speaking of UI: color adjustments work instantly, ‘snappy’…

Step #6
Proxy … smooth playback, transcoding of those 10secs in under a minute … no bad for my 'pocket calculator'.-

Yep, no recommended set-up for professional work to finance son’s College Fund, just a ‘stunt’ … at last "Houston, we have a pic!" …